Lupus La protein (SSB)
The protein contains 408 amino acids for an estimated molecular weight of 46837 Da.
Binds to the 3' poly(U) terminus of nascent RNA polymerase III transcripts, protecting them from exonuclease digestion and facilitating their folding and maturation (PubMed:3192525, PubMed:2470590). In case of Coxsackievirus B3 infection, binds to the viral internal ribosome entry site (IRES) and stimulates the IRES-mediated translation (PubMed:12384597). (updated: Oct. 25, 2017)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
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| Variant | Description |
|---|---|
| dbSNP:rs17160793 |
Biological Process
Histone mRNA metabolic process
IRES-dependent viral translational initiation
Nuclear histone mRNA catabolic process
Protein localization to cytoplasmic stress granule
RNA processing
TRNA 3'-end processing
TRNA 5'-leader removal
TRNA export from nucleus
TRNA modification
TRNA processing
The reference OMIM entry for this protein is 109090
Sjogren syndrome antigen b; ssb
Autoantigen la
La ribonucleoprotein domain family, member 3; larp3
DESCRIPTION
La is involved in diverse aspects of RNA metabolism, including binding and protecting 3-prime UUU(OH) elements of newly RNA polymerase III (see 606007)-transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs associated with hepatitis C virus. La protein was originally defined by its reactivity with autoantibodies from patients with Sjogren syndrome (270150) and systemic lupus erythematosus (SLE; 152700) (Teplova et al., 2006).CLONING
Chambers et al. (1988) determined the amino acid sequence of the La protein. The cDNA sequence encodes a protein of 408 amino acids. By immunoprecipitation and immunoblotting, it appears to be a single phosphoprotein of 46 to 50 kD. Chambers et al. (1988) also identified at least 3 antigenic epitopes on the La protein and predicted regions of the protein involved in RNA binding based on structural similarities with other RNA-binding proteins. See Bini et al. (1990). Grolz and Bachmann (1997) stated that there are 3 La pseudogenes. They also found that alternative splicing gives rise to 3 different mRNAs, all of which were expressed in all tissues tested, and all of which were translated into nuclear La protein in transfected mouse cells.GENE FUNCTION
Histone mRNA is destabilized at the end of S phase and in cell-free mRNA decay reaction mixtures supplemented with histone proteins, indicating that histones might autoregulate the histone mRNA half-life. Histone mRNA destabilization in vitro requires 3 components: polysomes, histones, and postpolysomal supernatant (S130). Polysomes are the source of the mRNA and mRNA-degrading enzymes. To investigate the role of the S130 in autoregulation, McLaren et al. (1997) fractionated crude S130 by histone-agarose affinity chromatography. They detected 2 separate activities affecting the histone mRNA half-life. The histone-agarose-bound fraction contained a histone mRNA destabilizer that was activated by histone proteins; the unbound fraction contained a histone mRNA stabilizer. The authors performed further chromatographic fractionation of the unbound material, which revealed only a single, approximately 52-kD stabilizer protein. McLaren et al. (1997) purified this stabilizer to homogeneity, partially sequenced it, and identified it as La. Addition of purified La to reaction mixtures containing polysomes resulted in the stabilization of a histone mRNA decay intermediate. This intermediate corresponded to histone mRNA lacking 12 nucleotides from its 3-prime end and containing an intact coding region. Anti-La antibody blocked the stabilization effect. La had little or no effect on several other cell cycle-regulated mRNAs. McLaren et al. (1997) suggested that La prolongs the histone mRNA half-life during S phase and thereby increases histone protein production. Conversion of a nascent precursor tRNA to a mature functional species is a multipartite process that involves the sequential actions of several processing and modifying enzymes. La is the first protein to interact with pre-tRNAs in eukaryotes. Intine et al. (2000) used an opal suppressor tRNA as a functional probe to examine the activities of yeast and human La proteins in this process in fission yeast. They found that an RNA recognition motif and Walker motif in the metazoan-specific C-terminal domain of human La maintain pre-tRNA in an unprocessed state by blocking the 5-prime-processing site, imp ... More on the omim web site
Feb. 10, 2018: Protein entry updated
Automatic update: Entry updated from uniprot information.
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 109090 was added.
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed